Jeffrey Marxen, who lived in Carmel Valley and had offices in La Mesa, was thrown from his 2005 yellow Honda Goldwing motorcycle after he ran into a curb while rounding a bend at about 10:15 p.m. Thursday, according to the San Diego County medical examiner's office.

Marxen, 60, struck a large blue metal canister around a water main line along the curb-line. Witnesses stopped to help, but the doctor had sustained serious injuries and was pronounced dead at the scene, the medical examiner's office said.

The San Diego Police Department's traffic division is investigating the crash, police officer David Stafford said.